Flexible control channels for unplanned wireless networks

ABSTRACT

A wireless node configured to communicate with a remote node using a timeslot structure. The timeslot structure includes a plurality of data channels and a plurality of control channels, wherein each of the control channels comprises a plurality of control units. The wireless node is further configured to assign any one of a plurality of control messages for the data channels to any one of the control units.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.11/960,537, filed Dec. 19, 2007, which is hereby incorporated byreference in its entirety.

BACKGROUND

1. Field

This disclosure relates generally to wireless communication and morespecifically, but not exclusively, to flexible control channels forunplanned wireless networks.

2. Introduction

A wireless communication system may be deployed in various waysdepending on the requirements of the intended application. For example,a planned deployment may be utilized for an application such as acellular network where seamless connectivity is desired over arelatively wide area. To reduce interference in such a network, thechannel or channels used by the wireless devices of the network may bedefined throughout the network.

Recently, there has been an increasing trend towards low-cost, flexibledeployment of wireless networks to support local area networks forindoor cellular usage and home access points. As a result, system designhas moved away from the planned and smooth interference model to onethat needs to be more robust to (1) bursty interference due to partialloading and (2) service through an access point that may not be the bestfrom an RF link perspective. This leads to greater uncertainty in thedesign with regard to the lowest signal-to-interference noise ratios(SINRs) that can be achieved as well as the extent of trafficmultiplexing that takes place. While data transmissions in such asetting have traditionally been taken care of through dynamicinterference avoidance, rate adaptation, and hybrid automaticrepeat-request (ARQ) techniques, control transmissions do not enjoy thebenefits of those techniques.

Accordingly, there is a need in the art for improvements in controltransmissions to enable greater robustness as needed as well asflexibility to traffic demands.

SUMMARY

In one aspect of the disclosure, an apparatus for wirelesscommunications includes a processing system configured to communicatewith a remote node using a timeslot structure having a plurality of datachannels and a plurality of control channels, wherein each of thecontrol channels comprises a plurality of control units, the processingsystem being further configured to assign any one of a plurality ofcontrol messages for the data channels to any one of the control units.

In another aspect of the disclosure. a method of communications includescommunicating with a remote node using a timeslot structure having aplurality of data channels and a plurality of control channels, whereineach of the control channels comprises a plurality of control units andeach of the control units is capable of carrying any one of a pluralityof control messages for the data channels, and assigning one of thecontrol messages to one of the control units.

In yet another aspect of the disclosure, an apparatus for wirelesscommunications includes means for communicating with a remote node usinga timeslot structure having a plurality of data channels and a pluralityof control channels, wherein each of the control channels comprises aplurality of control units, and means for assigning any one of aplurality of control messages for the data channels to any one of thecontrol units.

In a further aspect of the disclosure, a computer-program product forwireless communications includes a machine-readable medium comprisinginstructions executable by a processing system to communicate with aremote node using a timeslot structure having a plurality of datachannels and a plurality of control channels, wherein each of thecontrol channels comprises a plurality of control units, and assign anyone of a plurality of control messages for the data channels to any oneof the control units.

In yet a further aspect of the disclosure, an access terminal forwireless communications includes a processing system configuredcommunicate with a remote node using a timeslot structure having aplurality of data channels and a plurality of control channels, whereineach of the control channels comprises a plurality of control units, theprocessing system being further configured to assign any one of aplurality of control messages for the data channels to any one of thecontrol units, and a user interface configured to enable a user tocontrol communications between the processing system and the remotenode.

In another aspect of the disclosure, an access point includes a wirelessnetwork adapter configured to support a backhaul for a remote node to anetwork, and a processing system configured to communicate with theremote node using a timeslot structure having a plurality of datachannels and a plurality of control channels, wherein each of thecontrol channels comprises a plurality of control units, the processingsystem being further configured to assign any one of a plurality ofcontrol messages for the data channels to any one of the control units.

It is understood that other aspects of the invention will become readilyapparent to those skilled in the art from the following detaileddescription, wherein various aspects of the invention are shown anddescribed by way of illustration. As will be realized, the invention iscapable of other and different configurations and implementations andits several details are capable of modification in various otherrespects, all without departing from the scope of this disclosure.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of a wireless communications system are illustrated byway of example, and not by way of limitation, in the accompanyingdrawings, wherein:

FIG. 1 is a conceptual diagram illustrating an example of a wirelessnetwork 100;

FIG. 2 is a conceptual diagram illustrating an example of a timeslotstructure to support communications between two wireless nodes in awireless network;

FIG. 3 is a conceptual diagram illustrating an example of a timeslotstructure to support asymmetric data flows between two wireless nodes ina wireless network;

FIG. 4A is a conceptual diagram illustrating a more detailed example ofa timeslot structure to support asymmetric data flows between twowireless nodes in a wireless network;

FIG. 4B is a conceptual diagram illustrating an example of a timeslotstructure to support a change back to a symmetric data flow between twowireless nodes in a wireless network;

FIG. 5 is a conceptual diagram illustrating an example of a jammersituation that can occur in a home access point (HAP) setting;

FIG. 6 is a conceptual diagram illustrating an example of a timeslotstructure to support jammer avoidance mode of operation;

FIG. 7 is a conceptual diagram illustrating an example of a controlchannel configured as an OFDM symbol;

FIG. 8 is a block diagram illustrating an example of the functionalityof a wireless node; and

FIG. 9 is a block diagram illustrating an example of the functionalityof a processing system.

DETAILED DESCRIPTION

Various aspects of the disclosure are described below. It should beapparent that the teachings herein may be embodied in a wide variety offorms and that any specific structure, function, or both being disclosedherein is merely representative. Based on the teachings herein oneskilled in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. Furthermore,an aspect may comprise at least one element of a claim.

FIG. 1 is a conceptual diagram illustrating an example of a wirelessnetwork 100. The wireless network 100 is shown with several wirelessnodes 102. A wireless node may receive, transmit, or both. In thediscussion that follows, the term “receiving node” may be used to referto a wireless node that is receiving and the term “transmitting node”may be used to refer to a wireless node that is transmitting. Thesedesignations do not imply that the wireless node is incapable ofperforming both transmit and receive functions.

A wireless node may function as an access point, a relay point, anaccess terminal, or any combination thereof. In the example shown inFIG. 1, a number of the wireless nodes 102A-102B function together toprovide backhaul services to a number of access terminals 102C. Thenetwork 100 includes a wireless node 102A that functions as an accesspoint by providing an interface to another network (e.g., a cellularnetwork, an Internet service provider (ISP), the Internet, etc.) (notshown). The network 100 also includes two wireless nodes 102B₁ and 102B₂that function as relay points to connect the access terminals 104C tothe access point 102A.

The access point 102A may use one of many different wireless accessprotocols to support radio communications with the relay points 102B andaccess terminals 102C. By way of example, the access point 102A maysupport Evolution-Data Optimized (EV-D0), Ultra Mobile Broadband (UMB),802.11, or any other suitable access protocol. The access point 102A mayalso support the same or different access protocol with another network(e.g., a cellular network, an Internet service provider (ISP), theInternet, etc.) (not shown). By way of example, the access point 102Amay provide an 802.11 interface to the relay points 102B and accessterminals 102C and provide an EV-DO interface to the other network. Theactual wireless access protocols employed for any particular networkwill depend on the specific application and the overall designconstraints imposed on the system.

Four access terminals 102C are shown in FIG. 1. In this example, twoaccess terminals 102C₁ and 102C₂ are connected to the access point 102Athrough the relay point 102B₁, one access point 102C₃ is connected tothe access point 102A through the relay point 102B₂, and one accesspoint 102C₄ is connected directly to the access point 102A. Theconnections between the access point 102A and the access terminals 102Cmay be dynamically reconfigured based on any number of relevant factors(e.g., loading, failures, mobility, etc.). In some configurations of thewireless network 100, an access terminal 102C may be connected to theaccess point 102A through multiple relay points 102B or support multipleflows (e.g., telephony, messaging, etc.) through one or more relaypoints 102B. As an example of the latter, a first flow between theaccess point 102A and the access terminal 102C₂ may be routed throughthe relay point 102B₁ and a second flow between the access point 102Aand the access terminal 102C₂ may be routed through the relay point102B₂.

In some configurations of the wireless network 100, the flows betweenwireless nodes may be maintained using a time division multiplexingscheme. By way of example, each wireless node 102 in the network 100 maybe assigned designated timeslots to transmit and receive. For instance,the access point 102A may transmit to the access terminal 102C₄ duringodd numbered timeslots and the access terminal 102C₄ may transmit to theaccess point 102A during even numbered timeslots. Similarly, the accesspoint 102A may transmit to the relay points 102B₁ and 102B₂ during oddnumbered timeslots and the relay points 102B₁ and 102B₂ may transmit tothe access terminals 102C₁, 102C₂, and 102C₃ during even numberedtimeslots

FIG. 2 is a conceptual diagram illustrating an example of a timeslotstructure to support communications between two wireless nodes in awireless network. In this example, transmissions from a first wirelessnode to a second wireless node are designated by 202A, and transmissionsfrom the second wireless node to the first wireless node are designatedby 202B. More specifically, the timeslot structure 204A shown intimeslot 1 represents a transmission from the first wireless node to thesecond wireless node, the timeslot structure 204B shown in timeslot 2represents a transmission from the second wireless node to the firstwireless node, the timeslot structure 204C shown in timeslot 3represents a transmission from the first wireless node to the secondwireless node, and the timeslot structure 204D shown in timeslot 4represents a transmission from the second wireless node to the firstwireless node.

Each timeslot includes three data channels 206A-206C and three controlchannels 208, 210 and 212. The control channels may be used to providecontrol messages for the information carried in the data channels206A-206C. In the following example, the control messages will bedescribed in terms of a request/grant scheme to support a transmissionfrom the second wireless node to the first wireless node in timeslot 4.

In timeslot 1, one or more wireless nodes in the network intending toreceive data in timeslot 4 transmit a resource utilization message(RUM). By way of example, and with reference to FIGS. 1 and 2, the relaypoint 102B₁ may intend to schedule to receive from the access terminal102C₂ at the same time the relay point 102B₂ intends to schedule toreceive from the access terminal 102C₃. Depending on the distancebetween the relay point 102B₂ and the access terminal 102C₂ and thetransmission power of the access terminal 102C₂, a transmission from theaccess terminal 102C₂ may interfere with the reception at the relaypoint 102B₂. In that event, relay point 102B₂ may transmit a RUM on oneof the control channels 208, 210 and 212 before the scheduledtransmissions to indicate to other transmitting nodes that it desires acollision avoidance mode of transmission to mitigate interference. Insome configurations, a RUM may be weighted to indicate not only that areceiving node is disadvantaged (e.g., due to the interference it seeswhile receiving), but also the degree to which the receiving node isdisadvantaged. A transmitting node that receives a RUM may utilize thefact that it has received a RUM, as well as the weight thereof, todetermine an appropriate response. By way of example, if the accessterminal 102C₂ determines that the relay point 102B₂ is moredisadvantaged than the relay point 102B₁, access terminal 102C₂ mayelect to abstain from transmitting or may reduce its transmit power toavoid interfering with the relay point 102B₂. Alternatively, in theevent the access terminal 102C₂ determines that its own relay point102B₁ is more disadvantaged than the relay point 102B₂ (or any otherreceiving nodes that sent RUMs), the access terminal 102C₂ may ignorethe RUMs from the other nodes. In that case, the access terminal 102C₂may elect to transmit.

In the foregoing example, if the access terminal 102C₃ determines thatit may transmit during timeslot 4, it sends a “request” to transmit tothe relay point 102B₂ on one of the control channel 208, 210, and 212during timeslot 2. In accordance with the RUM-based scheme discussedabove, other neighboring transmitting nodes may not send a “request” totransmit during timeslot 2 if their own receiving nodes are lessdisadvantaged than the relay point 102B₂.

A “request” may take various forms. By way of example, a “request” mayinclude information regarding the timeslot and data channels which thedata is to be transmitted (e.g., timeslot 4 and all data channels206A-206C), and information regarding the data (e.g., the type of dataand quality of service expectations, transmission rate information,transmit power, etc.). In addition, a pilot signal may be transmittedwith the request. The pilot signal may be transmitted at a known powerspectral density or power level. In this way, upon reception of therequest and the pilot signal by the relay point 102B₂, the appropriatetransmission parameters for the data transmission during timeslot 4 maybe determined. Such parameters may include, by way of example, datatransmission rate, coding, etc.

In response to the “request,” the relay point 102B₂ sends a “grant” tothe access terminal 102C₃ on one of the control channels 208, 210, and212 during timeslot 3. The “grant” may include the parameters determinedby the relay point 102B₂ (e.g., data transmission rate, coding, etc.)from the “request” and pilot signal.

Upon reception of the “grant,” the access terminal 102C₃ transmits thedata on one or more data channels 206A-206C during timeslot 4. The relaypoint 102B₂ may acknowledge receipt of the data by sending an“acknowledgement” on the one of the control channel 208, 210 and 212during timeslot 5 (not shown).

It will be appreciated that the above request-grant scheme may beimplemented as a sliding cycle so that data may be transmitted duringevery transmit timeslot. By way of example, during timeslot 1, the relaypoint 102B₂ may transmit a RUM on the first control channel 208 toindicate that it is scheduled to receive a transmission during timeslot4, an “acknowledgement” on the second control channel 210 to acknowledgea transmission received during the previous timeslot (not shown), a“grant” on the third control channel 212 permitting the access terminal102CB₃ to transmit during timeslot 2, and “request” on the third controlchannel 212 requesting to transmit to the access terminal 102C₃ duringtimeslot 3. The relay point 102B₂ may also transmit data on one or moredata channels 206A-206C in timeslot 1 in response to a “grant” receivedfrom the access terminal 102C₃ during the previous timeslot (not shown).The mapping of the control messages to the control channels provided inthis example are intended to serve as an illustration only. Variousother static and dynamic mapping schemes may be implemented depending onthe specific application and the overall design constraints imposed onthe system.

Dynamic mapping of control messages to control channels in the timeslotstructure may provide certain advantages in a number of situations. Anexample will now be presented with reference to FIGS. 3 and 4A-4B, wherea flexible control channel mapping scheme may be used to supportasymmetric data flows.

FIG. 3 is a conceptual diagram illustrating an example of a timeslotstructure to support asymmetric data flows between two wireless nodes ina wireless network. In this example, transmissions from a first wirelessnode to a second wireless node are designated by 302A, and transmissionsfrom the second wireless node to the first wireless node are designatedby 302B. The first wireless node is initially configured to transmit tothe second wireless node during odd numbered timeslots 304A, 304C, andthe second wireless node is initially configured to transmit to thefirst wireless node during even numbered timeslots 304B, 304D. For thepurposes of illustration only, and without limitation, the followingexample will be presented with the first wireless node being the relaypoint 102B₂ and the second wireless node being the access terminal 102C₃of FIG. 1. In addition, various control message assignments will bepresented for clarity of explanation with the understanding that thecontrol messages may be mapped to different control channels.

As shown in FIGS. 1 and 3, the time division multiplexing scheme may bedynamically altered to support a change in traffic conditions. By way ofexample, the relay point 102B₂ may determine that it has more data tosend to the access terminal 102C₃ than the access terminal 102C₃ has tosend to the relay point 102B₂. Under these conditions, the relay point102B₂ may temporarily designate several of its receive timeslots astransmit timeslots and the access terminal 102C₃ may temporarilydesignate several of its transmit timeslots as receive timeslots. Thisconcept is shown in FIGS. 1 and 3 where the relay point 102B₂ designatestimeslot 6 as a transmit slot and the access terminal 102C₃ designatestimeslot 6 as a receive timeslot.

FIG. 4A is a conceptual diagram illustrating a more detailed example ofa timeslot structure to support asymmetric data flows between twowireless nodes in a wireless network. In this example, the relay point102B₂, which is originally configured to transmit during odd numberedtimeslots, decides that it will swap timeslot 4 from a receive timeslotto transmit timeslot. In order to transmit in timeslot 4, the relaypoint 102B₂ listens for RUMs on the first control channel 408 oftimeslot 1. Here, it should be appreciated that the relay point 102B₂ isnow receiving information during a portion of one of its transmittimeslots. To this end, the timeslots may be defined with guard timesbefore and/or after the control channels to facilitate the relay point102B₂ switching from a transmit mode of operation to a receive mode ofoperation and vice versa.

Depending on the results of an analysis of the RUMs received on thefirst control channel 408, the relay point 102B₂ may send a “request” totransmit on third control channel 412 to initiate a swap of one or moretimeslots. By way of example, the “request” may include a request totransmit during timeslot 3 (the relay point 102B₂'s normal transmittimeslot) as well as during timeslot 4 (a timeslot to be swapped). Thus,in this case, the “request” includes an inherent timeslot swap request.In contrast, in other implementations, the relay point 102B₂ may informthe access terminal 102C₃ of a timeslot swap by initially sending adedicated message (e.g., a request to swap).

The relay point 102B₂ may transmit other control information on thethird control channel 412. By way of example, the relay point 102B₂ maytransmit a “grant” in response to a “request” by the access terminal102C₃ to transmit during timeslot 2. In addition, the relay point 102B₂may transmit an “acknowledgement” in response to data received from theaccess terminal 102C₃ during timeslot 0 (not shown).

After receiving the “request” from the relay point 102B₂ during timeslot1, the access terminal 102C₃ may transmit a “grant” for timeslot 3 orfor timeslots 3 and 4 on the second control channel 410 during timeslot2. That is, the access terminal 102C₃ may issue a collective “grant” formultiple timeslots or may issue grants on a timeslot-by-timeslot basis(e.g., when the “requests” are made on a similar basis). In either case,the “grant” received by the relay point 102B₂ is transmitted on thesecond control channel 410.

Since the access terminal 102C₃ will not be transmitting data duringtimeslot 4, it will not need to transmit a “request” and pilot on thethird control channel 412 during timeslot 2. Instead, the relay point102B₂ may transmit a pilot during this period of time on the thirdcontrol channel 412. Here, it should be appreciated that the accessterminal 102C₃ is now receiving during a transmit timeslot (timeslot 2).As discussed earlier, guard times may be provided adjacent the thirdcontrol channel 412 in the timeslot structure to facilitate the accessterminal 102C₃ switching from a transmit mode to a receive mode and viceversa.

The access terminal 102C₃ may also transmit a RUM on the first controlchannel 408 in preparation for receiving a data transmission from therelay point 102B₂ in timeslot 5.

The relay point 102B₂ may then transmit data on one or more datachannels 406A-406B during the requested timeslots (i.e., timeslots 3 and4).

The relay point 102B₂ and the access terminal 102C₃ may continue toprovide appropriate signaling to support the swapping of timeslots foras long as the swapping is needed or allowed. By way of example, therelay point 102B₂ may listen for RUMs associated with contention fortimeslot 6 on the first control channel 408 of timeslot 3. The relaypoint 102B₂ may then send on the third control channel 412 a pilot and a“request” to transmit during timeslots 5 and 6.

The access terminal 102C₃ may use the first and second control channels408 and 410 during timeslot 4 to acknowledge receipt of the data fortimeslot 3, issue a “grant” for timeslots 5 and 6, and transmit a RUMfor timeslot 7. Similarly, the access terminal 102C₃ may use the samecontrol channels 408 and 410 during timeslot 6 to acknowledge receipt ofthe data for timeslots 4 and 5, issue a “grant” for timeslots 7 and 8,and transmit a RUM for timeslot 9.

At some point in time, the traffic flow between the relay point 102B₂and the access terminal 102C₃ may be changed back to a symmetric flow.FIG. 4B is a conceptual diagram illustrating an example of a timeslotstructure to support a change back to a symmetric data flow between twowireless nodes in a wireless network. For clarity of presentation, FIG.4B also refers to timeslots 1-4. It should be appreciated that the useof similar timeslot numbering is not intended to indicate that suchtimeslots are referring to the same points in time.

As shown in FIG. 4B, the request message transmitted by the relay point102B₂ on the third control channel 412 during timeslot 1 includes a“request” only to transmit data during timeslot 3. In other words, the“request” does not include a request to transmit data during timeslot 4.The relay point 102B₂ may also send a RUM on the first control channel408 in anticipation of receiving data in timeslot 4.

The access terminal 102C₃ then transmits on the first and second controlchannels 408 and 410 during timeslot 2 a “grant” associated withtimeslot 3, a RUM associated with timeslot 5, and an “acknowledgement”of the data received during timeslots 0 and 1. In addition, the accessterminal 102C₃ transmits on the third control channel 412 duringtimeslot 2 a “request” and pilot so that the access terminal 102C₃ maytransmit data to the relay point 102B₂ during timeslot 4. Operationsunder the original timeslot designation recommence after the accessterminal 102C₃ transmits a “grant,” RUM, and “acknowledgement” on thefirst and second control channels 408 and 410 during timeslot 4.

Another example will now be presented with reference to FIGS. 5 and 6,where a flexible control channel mapping scheme may be used to supportjammer avoidance modes of operation. FIG. 5 is a conceptual diagramillustrating an example of a jammer situation that can occur in a homeaccess point (HAP) setting. In this example, an access terminal 504 jamsa HAP 502 and vice-versa. More specifically, when the access terminal504 is transmitting to the HAP 508, the HAP 502 cannot receive from theaccess terminal 506. Similarly, when the HAP 502 is transmitting to theaccess terminal 506, the access terminal 504 cannot receive from the HAP508. In this situation, the two links 510 and 512 can alternate on thechannel without losing any timeslots in the transition as shown in FIG.6.

FIG. 6 is a conceptual diagram illustrating an example of a timeslotstructure to support a jammer avoidance mode of operation. In thisexample, various control message assignments will be presented forclarity of explanation with the understanding that the control messagesmay be mapped to different control channels. Referring now to FIG. 6,the HAP 502 sends a RUM on the first control channel 508 during timeslot1 to let the access terminal 504 know that it must back off on controlchannel usage. The RUM may be a reserved weight setting which requiresonly energy detection at the access terminal 504. Upon receiving theRUM, the access terminal 504 determines that it must backoff from usingthe third control channel 512 going forward. In this example, intimeslot 2, the access terminal 504 sends in the second control channel510 an “acknowledgement” for data received in timeslot 1 and signals tothe HAP 508 that it has received a RUM and will not be able to transmitor receive using the third control channel until it no longer hears aRUM, alternatively for some fixed period or a period that is a functionof the weight of the RUM. It also serves as a signal to the HAP 508 touse only the second control channel 510 to signal the access terminal504. In timeslot 3, the HAP 508 knows that it can only use the secondcontrol channel 510 to acknowledge data sent by the access terminal 504in timeslot 2. Correspondingly, the HAP 502, which sent the RUM, onlyuses the third control channel 512 to avoid jamming the accessterminal's 504 reception of control messages on the second controlchannel 510. A similar procedure may be applied if the access terminal504 wants to send a RUM to make the HAP 502 backoff to alternate controlchannel usage.

Many other advantages may be obtained through a flexible control channelmapping scheme. By way of example, there could be some wireless nodesthat are very disadvantaged in an unplanned deployment. To enable betterreliability on control, the control messages could be sent over twocontrol channels to provide more robustness. For higher data ratetransmissions or access terminals with less processing capability,control message assignments can be made with “acknowledgements” sent onthe third control channel (as opposed to the second control channel) toprovide more decoding time. Those skilled in the art will appreciateother advantages and uses for flexible control channel mapping inunplanned deployment, as well as other types of networks.

To increase flexibility, each control channel may be divided up intosub-channels, or control units. In one example, each control channelcomprises an orthogonal frequency division multiplexed (OFDM) symbolwhich is time division multiplexed within a timeslot. Referring to thetimeslot structures described earlier, the first control channel may bea first OFDM symbol, the second control channel may be a second OFDMsymbol, and the third control channel may be a third OFDM symbol. EachOFDM symbol may be divided into any number of control units with eachcontrol unit comprising any number of tones.

FIG. 7 is a conceptual diagram illustrating an example of a controlchannel configured as an OFDM symbol with 512 tones. Each control unitis defined to be 32 tones. Each control unit may be used to send acontrol message. A field within the control message may be used todetermine the type of control message being sent (e.g., request, grant,or acknowledgement). Alternatively, information mapping control messagetypes to control units may be exchanged between the wireless nodes.Several control messages may be carried by a single control unit, witheach control message type being assigned to a particular set of toneswithin the control unit. By way of example, “requests” may be assignedto the first 16 tones of a control unit and “grants” assigned to thesecond 16 tones in a control unit. Alternatively, or in addition to, acontrol message may be sent across multiple control units and acrossmultiple control channels. The control units may be of different sizeswithin a symbol, across symbols, etc. Also, a wireless terminal maytransmit on control units of one size and receive on control units ofanother size.

The alternative mapping schemes described thus far may be optimized tosupport communications with several other nodes by dedicating one ormore control units to exchanging control messages with each of the othernodes. The one or more control units assigned to support communicationswith any one of the associated nodes may be static, or dynamicallyaltered to support changing traffic conditions. Additional control unitsmay be assigned to support communications with any associated wirelessnode to provide more robustness at the expense of reducing the number ofassociated nodes that can be communicated with at any one time.

Although an example of a time division multiplexed control channelcomprising an OFDM symbol has been presented, those skilled in the artwill appreciate that the control channels may be implemented using othermultiple access technologies. These multiple access technologiesinclude, by way of example, time division multiple access (TDMA),frequency division multiple access (FDMA), code division multiple access(CDMA), orthogonal frequency division multiple access (OFDMA), or anyother suitable multiple access technology now known or developed in thefuture. Any suitable combination of these multiple access technologiesmay be used to implement multiple control channels with each controlchannel having multiple control units.

FIG. 8 is a block diagram illustrating an example of the functionalityof a wireless node. The following descriptive is informative in natureand broadly defines the functionality of each block. Only the pertinentfunctionality to various concepts described throughout this disclosurewill be described. Those skilled in the art will recognize that thesefunctional blocks can provide other functionality that is not describedherein. In this example, the wireless node 802 includes two functionalblocks: a network adapter 804 and a processing system 806.

The network adapter 804 provides both a transmitter and receiverfunction. The transmitting function includes modulating a carrier withinformation. The receiver function includes demodulating a carrier torecover information. The network adapter 804 provides various functionssuch as RF front-end processing, ADC, timing and frequency estimation,channel estimation, turbo coding etc. In summary, the network adapter804 provides the complete physical layer implementation of the wirelessnode 802.

The processing system 806, either alone or in combination with otherentities in the wireless node, is configured to implement allfunctionality above the physical layer. In at least one configuration,the processing system 806 is configured to use the transmitter andreceiver functions of the network adapter 804 to support communicationswith other wireless nodes in the network. The processing system 806supports a timeslot structure having a number of data and controlchannels with each control channel having a number of control units. Inthe transmit mode, the processing system 806 assigns various controlmessages to the control units and sends data on the data channels. Inthe receive mode, the processing system 806 receives various controlmessages carried by the control units and receives data on the datachannels. The control messages include, by way of example, a “request”to transmit, a “grant” in response to a request to transmit, an“acknowledgement,” and a RUM.

The wireless node 802 may function as an access terminal, access point,relay point, or any combination thereof. A wireless node 802 thatfunctions as an access terminal may include a user interface 808. Theuser interface 808 may include a display, keypad, speaker, microphone,and/or any other suitable interface that enables a user to operate theaccess terminal. The user interface 808 is used to control the data thatis transmitted and received by the processing system 806 over a wirelessuplink connection maintained by the network adapter 804.

A wireless node 802 that functions as an access point includes a networkadapter 804 that is capable of maintaining any suitable number ofwireless downlink connections with access terminals and/or relay points,as well as maintain one or more uplink connections to support thebackhaul. The uplink connection may be wired or wireless. By way ofexample, the access point may support a wireless downlink connection toa relay point and a wired uplink connection to another network (e.g.,the Internet). In this configuration, the processing system 806 utilizesthe data and control channels in the timeslot structure to efficientlyroute data between the upstream and downstream wireless nodes.

The processing system 806 may include one or more processors. Aprocessor may be a general purpose microprocessor, a microcontroller, aDigital Signal Processor (DSP), an Application Specific IntegratedCircuit (ASIC), a Field Programmable Gate Array (FPGA), a ProgrammableLogic Device (PLD), logic circuits, discrete hardware components, or anyother suitable entity that can perform calculations or othermanipulations of information.

The processing system 804 may also include one or more machine-readablemedia provide data storage and/or to support software applications.Software shall be construed broadly to mean instructions, programs,code, or any other electronic media content whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. Machine-readable media may include storageintegrated with a processor, such as might be the case with an ASIC.Machine-readable media may also include storage external to a processor,such as a Random Access Memory (RAM), a flash memory, a Read Only Memory(ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM),registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any othersuitable storage device. In addition, machine-readable media may includea transmission line or a carrier wave that encodes a data signal. Thoseskilled in the art will recognize how best to implement the describedfunctionality for the processing system.

FIG. 9 is a block diagram illustrating an example of the functionalityof a processing system. In this example, the processing system 900includes a module 902 for communicating with another wireless node usinga timeslot structure having a plurality of data channels and a pluralityof control channels, wherein each of the control channels comprises aplurality of control units, and a module 904 for assigning any one of aplurality of control messages for the data channels to any one of thecontrol units.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. §112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for” or, in the case of a method claim, theelement is recited using the phrase “step for.”

What is claimed is:
 1. An apparatus for wireless communications,comprising: a processing system configured to communicate with a remotenode using a timeslot structure having a plurality of data channels anda plurality of control channels, wherein each of the control channelscomprises a plurality of control units, the processing system beingfurther configured to assign any one of a plurality of control messagesfor the data channels to any one of the control units.
 2. The apparatusof claim 1 wherein the data and control channels comprise time divisionmultiplexed channels.
 3. The apparatus of claim 2 wherein each of thecontrol channels comprises an OFDM symbol having a plurality of tones,and wherein each of the control units comprises a portion of the tonesfor one of the control channels.
 4. The apparatus of claim 1 wherein oneof the control messages comprises a request to transmit.
 5. Theapparatus of claim 1 wherein one of the control messages comprises agrant in response to a transmit request.
 6. The apparatus of claim 1wherein one of the control messages comprises an acknowledgement that atransmission has been successfully received.
 7. The apparatus of claim 1wherein a first one of the control channels precedes a second one of thecontrol channels in a timeslot, and wherein the processing system isfurther configured to assign one of the control messages to the secondone of the control channels as a function of the processing capabilityof a transmitting remote node.
 8. The apparatus of claim 1 wherein theprocessing system is further configured to, in one timeslot, receive ona first one of the control channels and transmit on a second one of thecontrol channels.
 9. The apparatus of claim 1 wherein the processingsystem is further configured to switch between a first mode comprisingtransmitting on the data channels in every other timeslot and a secondmode comprising transmitting on the data channels in consecutivetimeslots.
 10. The apparatus of claim 9 wherein the processing system isfurther configured to transmit on first and second ones of the controlchannels in at least one of said every other timeslot in the first mode,and wherein the processing system is further configured to, in at leastone of said consecutive timeslots, receive on the first one of thecontrol channels and transmit on the second one of the control channelsduring the second mode.
 11. The apparatus of claim 1 wherein one of thecontrol messages comprises a request for a collision avoidance mode oftransmission.
 12. The apparatus of claim 11 wherein the processingsystem is further configured to transmit said one of the controlmessages on one of the control channels, the processing system beingfurther configured to communicate all other control messages with aremote node on one or more different control channels during at leastone timeslot following said one of the control messages.
 13. Theapparatus of claim 11 wherein the processing system is furtherconfigured to receive said one of the control messages on a first one ofthe control channels, the processing system being further configured toavoid using a second one of the control channels for communicatingcontrol messages with a remote node during at least one timeslotfollowing the message.
 14. The apparatus of claim 1 wherein theprocessing system is further configured to transmit one of the controlmessages on at least two of the control channels in one timeslot.
 15. Amethod of communications, comprising: communicating with a remote nodeusing a timeslot structure having a plurality of data channels and aplurality of control channels, wherein each of the control channelscomprises a plurality of control units and each of the control units iscapable of carrying any one of a plurality of control messages for thedata channels; and assigning one of the control messages to one of thecontrol units.
 16. A computer-program product for wirelesscommunications comprising: a machine-readable medium comprisinginstructions executable by a processing system: communicate with aremote node using a timeslot structure having a plurality of datachannels and a plurality of control channels, wherein each of thecontrol channels comprises a plurality of control units; and assign anyone of a plurality of control messages for the data channels to any oneof the control units.